<!DOCTYPE html>
<html>
  <head>
    <meta charset="utf-8">
    <title>Go by Example 中文版: 通道同步</title>
    <link rel=stylesheet href="site.css">
  </head>
  <script>
      onkeydown = (e) => {
          
          if (e.key == "ArrowLeft") {
              window.location.href = 'channel-buffering';
          }
          
          
          if (e.key == "ArrowRight") {
              window.location.href = 'channel-directions';
          }
          
      }
  </script>
  <body>

    <div class="example" id="channel-synchronization">
      <h2><a href="./">Go by Example 中文版</a>: 通道同步</h2>
      
      <table>
        
        <tr>
          <td class="docs">
            <p>我们可以使用通道来同步协程之间的执行状态。
这儿有一个例子，使用阻塞接收的方式，实现了等待另一个协程完成。
如果需要等待多个协程，<a href="waitgroups">WaitGroup</a> 是一个更好的选择。</p>

          </td>
          <td class="code empty leading">
            
          
          </td>
        </tr>
        
        <tr>
          <td class="docs">
            
          </td>
          <td class="code leading">
            <a href="http://play.golang.org/p/HyZo-7sKFy-"><img title="Run code" src="play.png" class="run" /></a><img title="Copy code" src="clipboard.png" class="copy" />
          <div class="highlight"><pre><span class="kn">package</span> <span class="nx">main</span>
</pre></div>

          </td>
        </tr>
        
        <tr>
          <td class="docs">
            
          </td>
          <td class="code leading">
            
          <div class="highlight"><pre><span class="kn">import</span> <span class="p">(</span>
    <span class="s">&quot;fmt&quot;</span>
    <span class="s">&quot;time&quot;</span>
<span class="p">)</span>
</pre></div>

          </td>
        </tr>
        
        <tr>
          <td class="docs">
            <p>我们将要在协程中运行这个函数。
<code>done</code> 通道将被用于通知其他协程这个函数已经完成工作。</p>

          </td>
          <td class="code leading">
            
          <div class="highlight"><pre><span class="kd">func</span> <span class="nx">worker</span><span class="p">(</span><span class="nx">done</span> <span class="kd">chan</span> <span class="kt">bool</span><span class="p">)</span> <span class="p">{</span>
    <span class="nx">fmt</span><span class="p">.</span><span class="nx">Print</span><span class="p">(</span><span class="s">&quot;working...&quot;</span><span class="p">)</span>
    <span class="nx">time</span><span class="p">.</span><span class="nx">Sleep</span><span class="p">(</span><span class="nx">time</span><span class="p">.</span><span class="nx">Second</span><span class="p">)</span>
    <span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">(</span><span class="s">&quot;done&quot;</span><span class="p">)</span>
</pre></div>

          </td>
        </tr>
        
        <tr>
          <td class="docs">
            <p>发送一个值来通知我们已经完工啦。</p>

          </td>
          <td class="code leading">
            
          <div class="highlight"><pre>    <span class="nx">done</span> <span class="o">&lt;-</span> <span class="kc">true</span>
<span class="p">}</span>
</pre></div>

          </td>
        </tr>
        
        <tr>
          <td class="docs">
            
          </td>
          <td class="code leading">
            
          <div class="highlight"><pre><span class="kd">func</span> <span class="nx">main</span><span class="p">()</span> <span class="p">{</span>
</pre></div>

          </td>
        </tr>
        
        <tr>
          <td class="docs">
            <p>运行一个 worker 协程，并给予用于通知的通道。</p>

          </td>
          <td class="code leading">
            
          <div class="highlight"><pre>    <span class="nx">done</span> <span class="o">:=</span> <span class="nb">make</span><span class="p">(</span><span class="kd">chan</span> <span class="kt">bool</span><span class="p">,</span> <span class="mi">1</span><span class="p">)</span>
    <span class="k">go</span> <span class="nx">worker</span><span class="p">(</span><span class="nx">done</span><span class="p">)</span>
</pre></div>

          </td>
        </tr>
        
        <tr>
          <td class="docs">
            <p>程序将一直阻塞，直至收到 worker 使用通道发送的通知。</p>

          </td>
          <td class="code">
            
          <div class="highlight"><pre>    <span class="o">&lt;-</span><span class="nx">done</span>
<span class="p">}</span>
</pre></div>

          </td>
        </tr>
        
      </table>
      
      <table>
        
        <tr>
          <td class="docs">
            
          </td>
          <td class="code leading">
            
          <div class="highlight"><pre><span class="gp">$</span> go run channel-synchronization.go
<span class="go">working...done</span>
</pre></div>

          </td>
        </tr>
        
        <tr>
          <td class="docs">
            <p>如果你把 <code>&lt;- done</code> 这行代码从程序中移除，
程序甚至可能在 <code>worker</code> 开始运行前就结束了。</p>

          </td>
          <td class="code empty">
            
          
          </td>
        </tr>
        
      </table>
      
      
      <p class="next">
        下一个例子: <a href="channel-directions">通道方向</a>
      </p>
      
      <p class="footer">
        <a href="https://twitter.com/mmcgrana">@mmcgrana</a> 编写 | <a href="https://github.com/gobyexample-cn">gobyexample-cn</a> 翻译 | <a href="https://github.com/gobyexample-cn/gobyexample/issues">反馈</a> | <a href="https://github.com/gobyexample-cn/gobyexample">源码</a> | <a href="https://github.com/mmcgrana/gobyexample#license">license</a>      </p>
      </p>
    </div>
    <script>
      var codeLines = [];
      codeLines.push('');codeLines.push('package main\u000A');codeLines.push('import (\u000A    \"fmt\"\u000A    \"time\"\u000A)\u000A');codeLines.push('func worker(done chan bool) {\u000A    fmt.Print(\"working...\")\u000A    time.Sleep(time.Second)\u000A    fmt.Println(\"done\")\u000A');codeLines.push('    done \x3C- true\u000A}\u000A');codeLines.push('func main() {\u000A');codeLines.push('    done := make(chan bool, 1)\u000A    go worker(done)\u000A');codeLines.push('    \x3C-done\u000A}\u000A');codeLines.push('');codeLines.push('');
    </script>
    <script src="site.js" async></script>
  </body>
</html>
